n. [ L. liquefactio: cf. F. liquéfaction. See Liquefy. ] 1. The act or operation of making or becoming liquid; especially, the conversion of a solid into a liquid by the sole agency of heat. [ 1913 Webster ]
2. The state of being liquid. [ 1913 Webster ]
3. (Chem. Physics) The act, process, or method, of reducing a gas or vapor to a liquid by means of cold or pressure; as, the liquefaction of oxygen or hydrogen. [ 1913 Webster ]